Join me as I speak with Dr. Jenicka Engler, developmental neuropsychologist and clinical scientist, as she explains and analyzes the high-quality research studies looking at the safety and effectiveness of sleep training.  
Spoiler alert- it shows that it’s safe and effective 🙂 


Have a listen!


Want to get your little one consistently sleeping 11-12 hours at night so you can be a functioning human?  Join my FREE training HERE:   

Eva (00:39):

Hey there, you’re listening to the My Sleeping Baby podcast, which is all about baby and child sleep. I’m so excited to teach you how you can get your little ones sleeping so that you can sleep too and enjoy parenthood to its fullest. I’m Eva Klein, your resident’s sleep expert, mom of three, founder of the Sleep Bible online coaching program, and lover of all things sleep and motherhood. If you’re looking for tangible solutions for your little one sleep woes or you simply want to learn more, this podcast is for you. For more information, check out and you can follow me on Instagram and Facebook @mysleepingbaby.m, and you can follow me on Instagram and Facebook at My Sleeping Baby.

Dr. Engler (00:45):

Dr. Jenna, thank you so much for coming on the My Sleeping Baby podcast. I’m so happy to have you here.

Dr. Engler (00:51):

Thank you for having me. We’re talking to some really important stuff today, so I’m excited to join.

Dr. Engler (00:55):

Yes. Okay. So before we dive in, tell everybody a little bit about yourself, your background and what you do.

Dr. Engler (01:03):

Sure. So I am a licensed psychologist in the Commonwealth of Massachusetts. My, um, background though is in, um, developmental neuropsychology. So I used to do a lot of neurodevelopmental neuropsychological evaluations, specialty in the really young sort of, um, toddlers and, you know, school-aged kids. And currently I am a clinical scientist, um, doing a lot of research work across psychiatry and neurology <laugh>.

Dr. Engler (01:31):

Amazing. And so that is your, I was asking you before, so you’re not, your full-time focus right now is research?

Dr. Engler (01:39):

That’s correct.

Dr. Engler (01:40):

Okay. And so tell everybody cuz this is, this is fascinating. So in the context of a research study or a multi-site research study, what, what exactly is your role, would you say?

Dr. Engler (01:54):

Sure. So, um, right now what I’m primarily doing is, um, looking at different types of outcome assessments. So how do we rate if somebody is improving, say, with an intervention or a new medication? And I’m training other, um, clinicians on how to properly do those assessments, making sure that they’re doing them in a way that, uh, will produce, um, meaningful data. And then also, you know, other things like scale creation and, and improving upon what we have. But, uh, I’m essentially on the sort of quality management side of, um, research at this point.

Dr. Engler (02:32):

Right. So your job in layman’s terms is to basically make sure that when a research study is taking place, that the, the quality of data that you’re able to get from this study is as high as it could possibly be.

Dr. Engler (02:50):

Yes. Along with, uh, a bunch of status statisticians and, and other people who, who, who like to crunch overs more than I do. Yes.

Dr. Engler (02:58):

Right, right. Okay. Amazing. So let’s dive right in because I reached out to you after I came across a reel that you had posted on Instagram. By the way, your Instagram feed is great. We’re gonna, we’ll link that at the end so that people can go and follow you. Um, but you had posted a reel, um, along with another pediatrician, all about a new study that had come out, um, about the latest findings on the safety of sleep training. Um, and this isn’t just any study, it was a what’s called a meta-analysis. So before we dive into what the findings are, you know, I reached out because I wanted you on this podcast to talk about these findings because they’re so important for so many different reasons. So first of all, what is a meta-analysis and how does it differ from any other research study that we might hear about?

Dr. Engler (03:54):

Sure. So, uh, I think it’s a great question because a lot of people, especially on Instagram and social media will say, oh, well there’s it’s research fact. And so what exactly does that mean? So in terms of quality of research, um, usually there sort of is a hierarchy. So at the very top, the hierarchy, like the, the most sort of generalizable, um, sort of confident we can be about research is, uh, through a meta-analysis, which essentially means like you’re sort of pooling data from multiple different randomized clinical trials usually. Um, and it’s like a really great way to say, okay, not just, you know, one piece of the puzzle here, but we’re looking sort of more broadly at all of these different studies pooling their data and then we’re sort of analyzing it. Um, so that’s, you know, if we see a meta-analysis and a meta-analysis is saying that, you know, there is really no differences in outcomes between say, parents that have done sleep training and parents that haven’t done sleep training, I’m a lot more comfortable saying, Hey, chances are there’s, you know, no harm caused by this.

Cuz there’s no difference between the two groups essentially. Right. Um, especially if that’s a longitudinal thing where they’re including United Studies that look at things over time, then I’m a lot more confident in those. Now under that you have a randomized clinical, um, um, randomized controlled trial, which essentially means that there is random assignment to either a placebo group, um, or, um, like an experimental group for example. And I, I’m just sort of summarizing cause there’s lots of different study designs and things like that, but Right. Um, essentially they’re, they’re comparing, you know, back to statistics 1 0 1, like a nu and a, um, alternative hypothesis, but they’re doing so in a way where, um, you know, you’re really making sure that you’re controlling for a lot of variables. That gives us, you know, a pretty confident ability to say, Hey, you know, I’m 95% sure these, uh, results and differences between these groups are not just due to chance.

Dr. Engler (05:52):

Right. Um, so a meta-analysis is obviously like it’s the cream of the crop in terms of Yeah,

Dr. Engler (05:57):

It’s the creme highest hundred percent. That’s, those are the ones

Dr. Engler (06:01):

Where level Yeah. And then it basically takes the numerous randomized controlled trials or the results from all the different randomized controlled trials and basically combines it into one mega study, basically. Right.

Dr. Engler (06:18):

So yes and no. What a lot of meta-analysis will do is they only wanna include like the quote unquote high quality, um, RCTs, the randomized controlled, um mm-hmm. <affirmative> trials. So, um, what they’ll do is they’ll sort of set a bar for saying, okay, well we only want studies who had, you know, um, uh, interventions that looked like this versus that, or Uhhuh <affirmative>, you know, had this many people in them or this many different treatment arms or intervention arms, things like that. Okay. Um, so the meta-analysis is really, as I said, where we’re, you know, very confident in the results cuz uh, science is always changing. Right. And we always get, you know, new, it’s like, is red wine good for you or not? Yeah. We’ve been slipping back and forth on that for so long. I, I couldn’t tell you at this point.

Dr. Engler (07:05):

Right. <laugh>. Right. Cause there’s, there’s so many, and I guess the problem, like that’s a really, the red wine, like that’s a great example of where when you don’t have a meta-analysis, which I, I don’t think we have one on that. And not that I’m a, I’m not a researcher, but now

Dr. Engler (07:19):

I’m gonna have to go look, look for it, come

Dr. Engler (07:20):

Out <laugh>. I guess the problem with that topic as an example is that there’s been so many different studies that have come out

Dr. Engler (07:28):

Exactly with

Dr. Engler (07:29):

Completely different conclusions that it’s so easy for a headline to say, you know, studies shows that red wine does X, Y, z, whatever it is, and it could be some really scary headline, but it’s ignoring the fact that there were, you know, 19 other studies showing the complete opposite conclusion.

Dr. Engler (07:49):

Exactly. And oftentimes those headlines don’t tell you it’s an R CT or if it’s a different type of study design as well. Yeah.

Dr. Engler (07:57):

Right, right, right, right. To me, it’s just like, it puts that one study in context of everything else. So when the headline says study proves X, y, Z, well, does it, is it actually proving that because are there 19 other studies disproving that? Or is it in the context of 19 other studies that are all more or less agreeing with the conclusion? Um, you know, like, I guess the dangers of smoking, smoking causing lung cancer. I don’t know when a meta-analysis came out proving a direct link between, you know, long-term smoking and lung cancer. But I can pretty much guarantee that if a study came out and said, oh, look, cigarettes are not so dangerous after all, um, <laugh>, it would be disproven by a hundred, 500 other studies. You gotta

Dr. Engler (08:48):

Look for the,

Dr. Engler (08:49):

We call it like, key. So that’s why the meta-analysis key is, is so important here.

Dr. Engler (08:54):

Yeah. So we look at like the preponderance of evidence, which is basically like, there’s always going to be some findings that are gonna go against what your sort of other findings say, right? Mm-hmm. <affirmative>. Cause if you replicate studies enough times, like sometimes things will not go the same way every single time. And, and it’s hard to explain sometimes when you look at the data, but mm-hmm. <affirmative>, um, generally speaking, you know, there’s a bit of variability even across studies because study designs differ the way they recruit for the studies differs. Yeah. So, um, the patient population,

Dr. Engler (09:27):

You know, they’re not, are different.

Dr. Engler (09:29):

Exactly. And depending on where, you know, in the world or in the country, they do them, you know, the things there, there can be some differences between it, but generally we wanna have a large enough sample size also where we can generalize those results. And so sometimes with some of these smaller studies, especially that have smaller ends or smaller sample sizes, it might not be as applicable, um Right. Or generalizable across, you know, larger spots of the population. But so, you know, meta-analysis at the top under that, we’ve got, um, RCTs, those randomized controlled trials under that we’ve got sort of like those longitudinal studies which are, um, or, uh, sort of, um, uh, studies that sort of track people over time. Mm-hmm. <affirmative>, so like one of the most famous ones is that, um, the nurses study where they’ve been tracking, you know, the every, you know, so often they sample, um, their database of nurses who’ve been answering the same questions for like 25 years or something like that. Um, and then under that, you know, you’ve got, um, case, case studies or single case designs and things like that. Right. Um, which really are, are useful for sort of generating hypotheses, but they don’t necessarily prove anything. Right.

Dr. Engler (10:35):

Yeah. Usually the conclusion says like, more research must be done <laugh>. Exactly. You know, it’s like that, like, interesting. Okay, we’ll think about this. Yeah. But now we might not, we might have to actually research this further.

Dr. Engler (10:49):

Exactly. So maybe those are useful for looking at correlations, which I think is a really important thing to bring up because a lot of people will quote research studies saying, oh, this causes this. And it’s like, whoa, whoa, whoa. That is a correlational sort of study design that is not something that can prove something that can prove causation. And there’s a lot of things that correlate, but they aren’t necessarily causal. Right. Right. So like, um, you know, I could, I could probably think of some great example here, but I

Dr. Engler (11:19):

<laugh> That’s

Dr. Engler (11:20):

Okay. Basically,

Dr. Engler (11:21):

I guess it’s like there were 10 people in this study and there were no, there was no control group. So off, off the bat, the conclusion that the study is gonna come to is gonna be, you know, interesting at best, but

Dr. Engler (11:37):

Yeah. And not really, you can look at associations, you can look at correlations, but I mean, it’s like, it’s like saying, oh, um, you know, uh, candy causes death. Right? Well, yeah, candy, or sorry, candy is associated with death. Right? Yeah. It’s like, okay, well it depends what

Dr. Engler (11:57):

Being alive is also associated with being alive. Exactly. Because 100 pe 100% of humankind dies eventually. Exactly. Right. But I hear what you’re saying, <laugh>.

Dr. Engler (12:08):

Yeah. If it, if it wasn’t that Monday, I could probably come up with a better example, but

Dr. Engler (12:12):

That’s okay. <laugh>.

Dr. Engler (12:13):

Yeah. Um, yeah. So,

Dr. Engler (12:15):

But another

Dr. Engler (12:16):

Words like installation causation is when when

Dr. Engler (12:18):

You see a headline saying, you know, research shows, it’s really important to understand that the media is not there to necessarily properly educate their, it they’re there for click, it’s, it’s, they’re there for clicks, right? Yeah.

Dr. Engler (12:35):


Dr. Engler (12:35):

Click baby their

Dr. Engler (12:37):


Dr. Engler (12:37):

To, they’re not gonna make sure that they’re letting you know that what they’re sharing with you is really, really high quality research versus that, you know, I wouldn’t call it bottom of the barrel, but like, oh, interesting outcome. Let’s look into this further type of research. And there is a massive,

Dr. Engler (12:55):

The nuance is lost when things are often reported by popular media. Even some of the good sort of journalists will get it wrong, but they usually do a good job of presenting both sides. So that’s actually how, you know, if what you are reading is like a good sort of, um, journalistic sort of endeavor, right? They usually will have both points of view, or at least something sort of neutral as opposed to like, overwhelmingly good or overwhelming bad. If somebody is just putting, um, sort of one point of view out there. Sometimes, um, you know, that might be suspect, um mm-hmm. <affirmative>, however, you know, it depends on, on what they’re trying to say as well. So usually, you know, when it comes to journalism, you’re trying to present facts and let people, you know, decide for themselves. But social media, it’s not usually that. It’s usually they’re trying to find the most following and they’re trying to please the algorithm. And what pleases the algorithm is things that are sensationalized Yes. And controversial. Mm. And one-sided. So, yeah. Um, I do often see that on social media, like research says, or studies show it tends to be wrong, or what people will say is like, this causes that. And as I said, I’m like, no, no, no, that is, yeah. That is not what that study said. That is a, an association causation at best, but, uh, a correlation at best not causation. Yeah.

Dr. Engler (14:16):

Yeah. So a hundred percent. But here we have a meta-analysis, which is yes. As we’ve established, you know, top of the totem pole cream of the crop,

Dr. Engler (14:27):

Well, several meta-analysis, clinical

Dr. Engler (14:29):

Data, data that we’ve gone

Dr. Engler (14:30):

Screening. Yeah. So, um, so

Dr. Engler (14:32):

Tell us about this.

Dr. Engler (14:33):

All right. So let, let me give a little bit of background. So, um, uh, Krupa, um, uh, and I, who’s the, the pediatrician mom, um, we, a while back had sort of posted an infographic of summarizing a lot of the sleep training research out there as a pediatrician who is very well followed on Instagram. You know, she was getting a lot of, um, you know, sort of, um, comments from people sort of, you know, saying that sleep training is harmful and this and that. And so she’s, you know, dispelling a lot of the miss out there. So we, as it stands, like especially with attachment, there’s a lot of attachment misinformation that’s going around. Mm-hmm. <affirmative>. So we had done that post originally and I had said, you know, Hey Copa, why don’t we do a reel on this and, you know, really get some reach.

And that’s when every troll in the universe sort of found us. And, uh, you know, the interrupts can be a, a, a place that if you go against what people are saying, they, they really make it personal and come after you. So really what we did was we summarized the current research. There was a more, um, recent meta-analysis that also found no, you know, real differences between groups of sleep trained and nons sleep trained, um mm-hmm. <affirmative> infants, you know, even, you know, years down the road. I mean, we have a few good meta analyses. We’ve got, you know, um, lots of RCTs, um, longitudinal studies, and they’re all varying degrees of quality. And that’s, I think the hardest part that, you know, it’s really hard to devise, um, you know, a really great study protocol for sleep training because it’s, um, it’s not as simple as, say, taking a pill or something like that.

Right. Yeah. So, you know, parents are gonna respond, um, you know, not always, you know, how you want them to in the middle of the night when they’re waking up with their child. Right, right. Of course. So you have to do something that’s gonna be realistic and work for families and also, um, prevent unblinding, which is, you know, tricky, which means that they would, you know, possibly become aware that they’re in the, you know Yeah. Control group, so to speak. Mm-hmm. <affirmative>. So, um, the, you know, the, the biggest sort of thing is that, uh, you know, we presented a, a pretty solid, um, you know, base of evidence, which we always want more. And I think that’s what we said in our, our caption as well, you know, based on the evidence that we have, which, um, is not nearly as much as we have on the positive parenting programs that include things like timeouts and things like that, which also are, are getting, you know, a very, um, sort of negative, uh, spin right now on social media.

But, um, you know, we don’t have quite as many studies as we would like. Cause we always want more evidence. Right. Of course. It’s always, of course, conrance of evidence, but we’ve got enough where, um, combined, you know, with the research base, with the real world evidence, you know, I’m comfortable saying, Hey, most likely there’s really no harm cause from this. Right? Yeah. We just don’t see it. We don’t see it in clinical practice. So, you know, I’m not seeing kids flooding, you know, well, when I was doing, you know, private practice, I wasn’t seeing kids flooding me with attachment caused injuries from sleep training. Right. It, it wasn’t a thing. Right. Um, you know, we didn’t really, um, have, you know, a lot of conversations that, you know, necessarily even had to do with attachment and sleep training back then. But now because it’s become this whole sort of zeitgeist on social media mm-hmm. <affirmative>

Parents are terrified that anything they do is going to harm this attachment relationship. And what parents don’t tend to realize is that, um, the attachment relationship is not affected by any one parenting practice. And I think that’s where a lot of folks are getting sort of carried away. It’s like, oh, well if I don’t breastfeed, if, you know, I do sleep training if I don’t baby wear all the time. And you know, these things that people think go along with attachment practices because of, you know, attachment parenting and other Yeah. Sort of things. They, they think they’re going to spoil their attachment when in fact, um, you know, we actually don’t have to get it right all the time and shouldn’t be getting it right all the time Yeah. To promote attachment. That’s actually one of the biggest misconceptions. Like over responsiveness is also not good.

Dr. Engler (18:40):

No. So that’s like harmful on the other end of the spectrum.

Dr. Engler (18:44):

Exactly. Like the happy medium and what the attachment research actually shows is that good enough, responding is truly the sweet spot. So you wanna be hitting somewhere between 50% to, um, you know, under that 95%, I usually say aim for 75% of the time. Yeah. Um, you know, that’s, that’s where I try to aim with my toddler, um mm-hmm. <affirmative> or when she was an infant still. But, um, you know, that’s, I think the perspective that’s being lost. It’s like, you know, with the gentle parenting moments, you need to be responding all the time. It’s all about connection, all about responsiveness all the time. And I’m like, that’s actually not what the research shows. Right. So, um, and again, we always wish that we had more research, but, um, you know, when, when people start coming after you online saying that, because you are saying that there’s no harm caused by sleep training based on the research that we have, including a, a new, you know, large meta-analysis and people are saying that I’m promoting child abuse and Yeah. Um, you know, mistreatment of kids and, um, you know,

Dr. Engler (19:46):

Quite farfetch, horrible

Dr. Engler (19:47):

Doctor. It’s pretty personal.

Dr. Engler (19:49):

Say the very least. A little, a little bit, you know, far farfetched <laugh> and, uh, not, not, uh, I mean ironically quite abusive themselves, but, you know, will, I guess digress from that. My question for you is when some of these quote unquote experts, you know, come out and they talk about how maybe they don’t necessarily accuse you of child abuse, but they disagree with the practice of sleep training and they say, you know, research shows or studies show that it can, um, rupture healthy attachment and cause lifelong trust issues because your baby is learning that when, that they’re not, they can’t expect you to respond to them. Um, and so they’re gonna start, they’ll stop calling out for you. They’re not learning how to sleep, they’re learning that you’re not gonna come to them anymore.

Dr. Engler (20:43):

Yeah. So

Dr. Engler (20:44):

What is

Dr. Engler (20:45):


Dr. Engler (20:47):

If anything? Like, is there any shred of evidence that, as I said, is maybe taken out of context? Like the Oh, this hypothetical, oh look, smoking isn’t actually that bad for your lungs. That’s

Dr. Engler (21:00):

From the Romanian orphanage study. Um, okay.

Dr. Engler (21:03):

So tell us about the Romanian orphanage study and what that Yeah. What that actually looked like.

Dr. Engler (21:09):

So, so, um, some folks, uh, I wanna say, oh gosh, were these, uh, I think they were clinicians. I don’t even think they were necessarily, um, researchers so to speak, but they, um, would notice that when they would go to these orphanages in like Romania and Eastern Europe, it was quite enough to hear a pin drop. The kids weren’t crying mm-hmm. <affirmative>. And so they studied this and they found that, um, it’s because of the severe, um, sort of neglect in these institutions where these kids were not being responded to regardless of what time of day it was. Right. Yeah. So they learned that if I cry, nothing happens because

Dr. Engler (21:52):

For young kids

Dr. Engler (21:54):

Yeah. Day and night, it wasn’t just regarding sleep. Yeah. Um, but it was more, I mean, it’s neglect, it’s, um, you know, it’s abuse, right? Mm-hmm. <affirmative>, but again, you know, they’re institutionalized. There wasn’t, you know, a whole lot that could be done about it. Um, and so what happened was they realized that, um, because again, young kids crying is a means of communication, but there’s lots of different reasons why they cry. Right. It’s our jobs figure out, well, why are they crying? Yeah. It means that they’re trying to communicate something, but it doesn’t necessarily mean that it communicates what you think it’s communicating all the time. Correct. Right. Um, so what they found was that the babies would stop signaling, they wouldn’t cry anymore because they knew no, it wouldn’t do anything. Right. So they learned that it wasn’t actually, you know, getting their needs met, so they weren’t going to expend the energy doing it.

Dr. Engler (22:40):

Right. So often, and realistically, how long of a period of time d did, did each of those children realistically have to cry for day in and day out and not get responded to at like, at all before they then left?

Dr. Engler (22:57):

Oh. That, that is a long term thing. And I think that’s also where there’s a lot of misconceptions between sleep training and letting a baby cry for, you know, 10, 15, 20 minutes. These, these are kids who, babies who would really be left to cry for long durations of time over long periods of time. Right. Um, you know, they, aside from getting their, you know, sometimes the, not even getting their most basic needs met at being fed and changed and things like that. Right. Um, you know, they, they really were, did not have a lot of human contact at all. They were in their cribs all the time. I mean, that was the other thing. They, it was not an enriching environment otherwise.

Dr. Engler (23:38):

I mean, that’s heartbreaking. Like honestly

Dr. Engler (23:40):

Gone. And it’s a very

Dr. Engler (23:42):


Dr. Engler (23:42):

Extreme, extreme sort of situation. Yeah. Um, and you know, things have thankfully improved for the most part I hear anyways, you know, it’s not quite as bad as it used to be, but, um, at least knock on wood mm-hmm. <affirmative>. Um, but so the comparisons being made, um, and you know, saying that, hey, this is what happens and, and yes. So there are some parts of that that are true in the behavioral sciences. Right. So if the crying is serving a function of X and that same function is not that same sort of, um, you know, that’s not being met, then they’re gonna try something different, right? Mm-hmm. <affirmative>, because, you know, they might up the ante. So instead of, you know, just crying, maybe they’ll start, you know, biting or, you know, something else. Cause Yeah. They need to get their need met in some way.

They’ll up the ante or they’ll do something different. Right. Right. Um, you know, there’s lots of different ways that kids will communicate when they’re little and, um, I think the, the hardest part is that it, it makes sense. It has like sort of this face validity. Yeah. But there’s just not an evidence base that shows that that’s, you know, what happens. And there’s also no way for us to really separate it out. Right. Yeah. So like there’s no way for us to say, okay, you stopped crying because you learned to self-sooth versus you stopped crying cuz you learned that you shouldn’t signal and work that nobody was coming. Yeah. Right. There’s no way to differentiate those. We can’t ask babies. Well, which one was it <laugh>?

Dr. Engler (25:12):

Yeah. Did you

Dr. Engler (25:13):

Ourselves sooner this? Right. So we have to sort of look for, um, sort of other clues, right. And, um, that’s sort of the debate that people will have about this and mm-hmm. <affirmative>, you know, the science isn’t a hundred percent on that. Right. Like, we can’t say, but what we can say is that if you look at the two different groups and there’s no difference between the groups. Yeah. To me that says, you know, no harm no foul. And if there are potential benefits, um, then, you know, I think that that sort of makes the case because I think what gets lost in this whole conversation about sleep training and attachment and all these issues is that, um, we do have a pretty robust research base that shows, you know, that maternal mental health and parental mental health is actually quite important for the attachment bond. So things like untreated postpartum depression, for example, can lead to attachment issues if untreated. Right. Right. Because, um, you know, really depressed moms are not going to be as responsive to their infants. They might not be able to get out of bed. They, um, you know, might not be able to smile and, you know, talk mothers with their, your baby because they’re too tired or too depressed to do so. Um,

Dr. Engler (26:23):

And we have very conclusive research, I’m assuming on the connection between the two.

Dr. Engler (26:30):

Yeah. So can’t imagine it’s, it’s, it’s actually funny because, so that would be correlational, it’s correlational art. Okay. Um, because the only causational information that we have right now on what actually causes attachment issues are se is, is actually abuse and neglect. Mm-hmm. <affirmative>. So things like sexual physical trauma, um, neglect, um, beyond just, you know, emotional neglect. Yeah. Um,

Dr. Engler (26:56):

Like I’m, the term I’ve heard I keep hearing is long-term childhood stress.

Dr. Engler (27:00):

Exactly. That’s the term that I get those adverse childhood, um, experiences. Exactly. Mm-hmm. <affirmative>, but this is like something that it, like the attachment bond is not something that can be broken easily and your, is it broken by, you know, short term sort of things. It is really more, can

Dr. Engler (27:18):

You repeat that again? Cause I

Dr. Engler (27:20):

Think responsiveness and getting your needs met over time,

Dr. Engler (27:23):

I need you to repeat that again about how it’s that you cannot break an a, a, a healthy attachment bond <laugh> in a very short period of time. Yeah. Because that’s massive. So

Dr. Engler (27:35):

Say, okay, so

Dr. Engler (27:36):

Emphasize that one.

Dr. Engler (27:36):

Yes. You have, if you have a secure attachment. So there’s two types of attachment that when we talk about, so we talk about secure attachment and then insecure attachment. Now within insecure attachment, there’s different types that’s like, you’re avoidant, you’re anxious, you’re disorganized, like, you know, all those different sort of subsets of attachment. But if you have a secure attachment, um, a short-term intervention, which is for the most part sleep training, most people don’t who don’t do sleep training for, you know, months and months and months and years and years. You might have to revisit it every so often. Yeah. But usually it’s a short term sort of thing. Like a few weeks here, you know, and then maybe you just like I can do sleep training ’em after, you know, a, a developmental progression or something, um, or when they’re, you know, a bit older, but you know, something that if it was there and if it was secure to begin with, a short term sort of intervention like that is not going to make or break it. It’s, it’s just one piece of a much larger puzzle. And as I said, you know, the ideal responsiveness is really somewhere between that 50 to 95% of the time. So, you know, kids are asleep maybe what, 12 hours a day and if they’re only waking up crying for a very small percentage of that and you’re not responding all of the time to that, then you know, you’re still within your 50 to, you know, 95% of the time responsiveness. Right. Um, now is it, you know, something to say that you should just, oh, go ahead.

Dr. Engler (28:59):

Oh, I was just gonna say sleep training, the way that I see it is that it doesn’t necessarily, you know, need to involve not responding at all. You know, like exactly a fried out or extinction method. There are many other approaches that you can use that involve, you know, providing your baby with physical and emotional support to help them through this learning curve so that you are still responding, but just not the way that they want you to respond.

Dr. Engler (29:27):

Exactly. It’s like a, a diminishing sort of, uh, pattern of sort of, uh, richness with your interactions. Yeah. So, uh, under responding is, is what I like to sort of call it sometimes. So you’re still responding, you’re just not responding with the coing and coddling quite like you would in other times

Dr. Engler (29:45):

With exactly the way that they are used to being responded to, you know, exactly. In that moment. But then a lot of these, you know, I guess the critics or, you know, the cynics of the sleep trading will say, well, this is gonna cause their cortisol levels to go up, it’s gonna cause the, these this really high level of stress in your baby. Yeah. Because research shows, right. This is, that’s the, you should put it like, it should almost be like a trademark term. Like research shows <laugh> that when you do any form of sleep training, it’s gonna cause your baby’s stress levels to heighten your stress levels might go down, but your baby is gonna be in this heightened level of stress. Yeah. Can you, so

Dr. Engler (30:29):

I think that’s the middle miss, the middle miss study. So the middle miss study is a very low quality study because what they did was they looked at sleep, uh, a very small m I think it was like 30 kids or something. Um, they looked at a very, and might I say I might be, uh, I might be a little generous with 30, I might have been closer to like 22 or something. Yeah. Um, but they, what they did was they measured cortisol levels after sleep training or not. Right. Some, something to that extent. And so one of the main problems with that study was that they didn’t take any baseline levels of, of cortisol. Right. Right. So there’s individual differences between babies. Right. And you have to compare yourself pre-intervention and post-intervention and not to do it that way. It’s like it’s meaningless data.

Yeah. Um, there was a more recent study actually just, um, I, I just came across it that is looking at cortisol levels longitudinally, which did find some elevated cortisol, but I also question the validity of using cortisol as an end all be all for, um, you know, sleep training versus not sleep training. Because there’s a lot of different reasons, like your cortisol levels change throughout the day. Right. Um, they change situationally and so, you know, obviously nobody’s getting these babies up in the middle of the night to do a blood draw right. After they’ve been Right. You know, crying. Right. So like, there’s all these different things. Like I, I just don’t necessarily know that’s the best way to sort of mm-hmm. <affirmative> measure, um, you know, really anything. Right.

Dr. Engler (31:57):


Dr. Engler (31:58):


Dr. Engler (31:59):

If it’s just that little, you know, I I a snapshot like a little one time of day that they’re measuring cortisol. It’s also not taking into account that when humans of any age are overtired because they’re not getting enough sleep over 24 hour period, guess what happens? People <laugh> guess what goes up your,

Dr. Engler (32:23):

Well, exactly. There’s so many con and those are what we call confounding variables. Yeah. So for me, I look at that and I say, well look, I mean, you know, at face value it looks like, yeah, that would make perfect sense, except that it really doesn’t because our cortisol values fluctuate throughout the day. You’d have to take it at like the same time. You’d have to, you know, account for things like recent illnesses. Um, you know, are they overtired? Because again, you know, once you get overtired then you know, adrenaline and other things can start going too. Yeah. Um, so there’s just a lot of things and I don’t necessarily think that that’s the, the end all be all for mm-hmm. <affirmative>, um, sort of measuring, you know, if this is harmful or not. Right. Uh, because there’s no way to control for all the external variables that influence cortisol levels.

Um, and you know, I, I think again, looking at some of the more robust research that we have, you know, if, you know, five years down the line there’s no differences between groups, um, you know, you control for all those variables and you’re, you’re not finding anything, chances are, you know, it’s, there’s probably nothing to be said there, but obviously we wanna keep replicating and it’s really hard cuz as you mentioned, there’s so many different ways to do sleep training for kids. Right. And of course what one person thinks of his sleep training is not necessarily what the study actually looked at or what another person’s doing. And I think the, the biggest sort of takeaway I have is that, you know, when people are saying research says you ask for a citation, what is your, uh, can you cite your source? What is the name of the study or the year so I can look it up and you can usually look up the abstracts.

Um, yeah. You might not have access to the full article, but usually the abstract will sort of tell you everything. And I’ll tell you what the study design was usually how many people were in it. Mm-hmm. <affirmative>. Um, and you can gather some more information based on that. And sometimes, you know, even um, the research that’s being quoted is, is like, okay, well that’s not actually what that study says when you go look at the study, they’re sort of drawing improper conclusions sometimes from the research. Right. So oftentimes the research will say something like, oh, this is exploratory, more works need to be done. But then somebody else is saying, oh, well research shows that this causes this and is like, no, that’s actually not what they’re saying. They’re saying this is an interesting finding and we need to replicate it more at scale. Right. Um, before we can draw any conclusions like that. So,

Dr. Engler (34:40):

Which is exactly what this specific cortisol study is. Right. It was 20 babies who by the way were also doing sleep training in a sleep lab. They weren’t even at home. So they were, there were, um, cuz I know it was done in Aus, either Australia or New Zealand where they have these, um, in hospitals, they have these sleep schools or sleep clinics where they have, I don’t know if it’s nurses or other hospitals staff or technicians that teach these babies how to sleep. I’m not really quite sure the ins and outs of this, but um, already this is not the same home environment as the baby is in. So that’s already so probably a massive, you know, call a massive right there.

Dr. Engler (35:21):

I didn’t realize that about that study. That’s even one more reason why it’s sort of is less valid in my cause I mean, you’re gonna raise hundred this cortisol level by separating them from their parents.

Dr. Engler (35:32):

Yes. Yes. And holding them in a strange environment,

Dr. Engler (35:35):

A strange

Dr. Engler (35:35):

Environment with these strange lab technicians who are putting them to sleep. Um, and I remember reading that study and I’m almost positive that the conclusion says something along the lines of, you know, this was interesting, more research needs to be done. Yeah. Do you think that the actual researchers, the actual clinicians who you did this study, do you think that they had any idea that this study would be used as ammunition for the anti-slip training world to sort of do its thing and, you know, scare people to death, to do sleep training <laugh>?

Dr. Engler (36:13):

You know, I don’t, I don’t think so because if they were trying to prove something like that, they, as I said, they would’ve done pre-intervention cortisol levels as well. Right. I think they were really just looking to say, Hey, is there something here that we need to do more follow up studies on?

Dr. Engler (36:28):


Dr. Engler (36:29):

And then they realized like, oh, you know, this probably, I don’t even think that they ended up doing the, the follow up study for that themselves. Cause they sort of realized that it, it wasn’t really all that meaningful.

Dr. Engler (36:42):

Right. Right. And at the same time, I don’t know how much social media exposure these clinicians have, but I would imagine that if they did have that exposure, they themselves be looking at some of these posts and going, that is not what my study concluded <laugh>. I don’t know what this person is talking about, but I did that study and that’s not what that study says. Thank you very much. Um, so yeah, it’s kind of, I don’t know if they like chuckle about it or if they’re horrified that, you know, their research is being used as being sort of twisted in a way to sort of help this already formed conclusion that just sort of is relying on something like this to back it up when, when really that’s not what this study’s actually doing.

Dr. Engler (37:31):

Yeah. I mean it’s, uh, it’s hard to know what, you know, cause I don’t know those researchers personally. Um, but you know what, I think the, when I sort of talk to parents, I, I always say the biggest takeaway here is that again, any one parenting practice in isolation isn’t going to make or break attachment. It’s not going to, um, you know, really have lasting effects beyond what the context of your other relationships and interactions are. Right. So like if you don’t interact with your child at all during the day, and then only time that you have to interact with them is at night, then yeah. I would say then that’s really important that you’re responsive to ’em at night. Like mm-hmm. <affirmative>, that’s your only time that you’re interacting with them, but if you’re interacting with them throughout the day or you’re having other touchpoints, you know, morning when they come home from, you know, daycare, if they’re in daycare, you know, from then until time they go to sleep, you know, it, it’s also, it’s, it’s a fine line because if you are stressing yourself out to the point where you are that parent who I’ve gotta respond every time, I gotta respond every time, and it’s taking a toll on your mental health.

I mean, you’re gonna be more irritable with your child if you’re not taking care of your own needs. If you’re not sleeping well also. Yeah. Um, so, you know, you might be more likely to yell at your child or to get frustrated with them and they’ll pick up on that stuff too. Yeah. So, you know, at the end of the day what I try to say is, look, you know, I’m not in favor of sleep training, I’m not against sleep training. I, I am for, I’m pro-family. So yeah. Whatever it is that’s going to work pro

Dr. Engler (39:00):

Choice for your families. Pro pro

Dr. Engler (39:03):

I’m very

Dr. Engler (39:03):

Pro this choice

Dr. Engler (39:04):

And, um, and you know, the, the research says that it, there’s no evidence of harm and obviously we would like to have more research, but, you know, a lot of parenting issues we actually don’t have any research on at all. Yeah. Um, and the stuff that we do have research on even really robust research, as I said, like things like timeouts that is now getting vilified as well. So it’s not actually about the research. People have opinions and they have, you know, very strongly formed opinions and if Yeah. Um, you know, the research goes against that opinion, they’re gonna find some way to pick that apart too, and Yeah. Um, so it’s not really about the research. Yeah. But at the same time, I, I think it is important for parents to be informed consumers of, um, social media information. So being able to identify, you know, when somebody is saying something is research based, when fact it’s not research based or, uh, like what does that research base mean? Like, and you go look up the study and say, oh, this is like a pilot study with 10 people in it and they’re saying it, this causes

Dr. Engler (40:01):

Us and no control group, no control,

Dr. Engler (40:04):


Dr. Engler (40:04):

Control group. So we Exactly. Yeah. And you know what, I’ll tell you, I mean, uh, to me, like one of the main reasons why I wanted to have you on my podcast, so talk about this is because I know I mentioned this before we started recording that in my, I would say my quasi previous lifetime, I worked as a lawyer in a very big academic hospital here in Toronto, in the legal department, um, drafting and negotiating the hospital’s clinical trial agreements and other such res research related agreements. So I was, this is what I did every single day for a number of years. Um, and while I wasn’t the clinician doing the research, I learned very quickly what the difference was between a clinical trial agreement versus, um, a retroactive, you know, study, like looking at data from the past versus, you know, some other, you know, pilot study, a multi-site study versus a single site study.

Like I, I learned because again, it was all in the various different agreements that I was negotiating every single day. Um, I was talking to Pfizer before it was cool to talk to Pfizer before people really cared about what Pfizer was doing. Um, but, and so even though I’m not a clinician, I still have that background knowledge to be able to question a headline when I see research says X, Y, Z because mm-hmm. <affirmative>, I know that there is a very big difference that not all research is created equally, but also recognizing that the only reason why I know that is because of what I did for a living for a number of years. Yeah. Most people don’t know this. Yeah. Most people see research proves and they just, they take that at face value because they don’t have the background to be able to question what it, what that headline actually means, what the research is actually showing.

Um, and so I’m so happy that you were able to come on here to first of all explain to people that not all, why not all research is the same. Um, b what the research that we have today actually shows about sleep training and what it doesn’t show. And c empower parents to be able to make the choice that works best for them given that the research shows that there are multiple ways to be able to raise happy, healthy, emotionally stable children, and that everyone has the permission that they need to do what feels best for them because all those options are are safe and healthy as long as it works for you. Right.

Dr. Engler (42:47):

Yeah. I mean, and the biggest one that I, I, you know, I hate to get on my soapbox here, but I guess it’s a good place to do it. Yeah. Um, the, the most concerning thing that I’ve been seeing on social media lately is, um, the push against sleep training and the push for bed sharing instead of sleep training. Mm-hmm. <affirmative>. And that’s where I get really upset because, you know, uh, 3,500 kids a year just in the US alone die from, you know, SIDS or s u i, uh, sudden unexplained infant death syndrome, which, you know, can include things like bed sharing and for the fact that they’re saying, oh, well you can’t do sleep training that causes harm. I’m like, no, there’s no evidence it causes harm and it certainly doesn’t cause death. Um, where, you know, obviously not all beds sharing, most people who beds share their, their infant is not going to die, but there’s no reason that any infant should be dying due to something so completely preventable. And so the fact that, you know, people are saying beds sharing is a safer alternative to sleep training that really grinds my gears is both a clinician and a researcher and a parent. Yes.

Dr. Engler (43:53):

Because you’re immediately goes people

Dr. Engler (43:55):


Dr. Engler (43:55):

People had their or my brain goes to, which is prove

Dr. Engler (43:58):

It, have sids Yeah.

Dr. Engler (43:59):

Prove it. Yeah. Where is that data to back that up?

Dr. Engler (44:03):

Yeah, exactly. And that’s, I think the, the biggest thing, you know, be an educated consumer, makes sure that you are, you know, asking what’s your source? And then you can go check it out. The problem is mm-hmm. <affirmative> is that, you know, you sort of need to remember back to your high school stats to be able to understand and how to digest some of, um, those abstracts and things like that. But, um, you know, usually, um, more or, uh, sort of more nowadays are including sort of layperson summaries and things like that. Mm-hmm. <affirmative>, there’s a big push to sort of, um, make the science more accessible for the people, um, who aren’t necessarily, you know, able to digest all of the stats. Um, but I think, you know, chances are if it, like I I I always like to just say the sniff test, like if it smells rotten chances it probably is <laugh>.

Dr. Engler (44:53):

I I hear you. And this is, this is such gold. I mean, I feel like there are, I actually just right before we started recording this, I was on a, a call, I had a prospect call me. Um, I had a, a a, a quick check-in call with her, you know, just talking about like whether or not she wanted to work with me. And she fully admitted that she had gone down that rabbit hole of, you know, googling the, you know, dangers of sleep training and as a, a sleep deprived, vulnerable postpartum mom. And I emphasize the word vulnerable because I do think that postpartum women are in a vulnerable, um, population. I get Oh, a hundred percent. So I get like the mama bear in me comes out where, you know, I get so protective over my people. Like I just wanna shield every single one of them from all that very dangerous and predatory bs that can get in the way of moms doing what they need to do to reclaim their health.

Um, yeah. And to reclaim and, and actually have a healthy relationship with their baby. Yeah. <laugh> because their tank is full. So I thank you so much for coming on and talking about this all in more detail, how the research works, you know, the nitty like some of that needy gritty things that I think people really need to understand so that, you know, when you are saying, no, no, no, like this meta-analysis really does give us like the best quality proof we can get right now. That this is a safe and effective choice that you can make it, it really does give permission to a lot of moms to be able to do what they desperately need to do. So thank you so much for, for coming on today. I appreciate it.

Dr. Engler (46:42):

Yeah, thank you for having me. And, uh, if you wanna get more information on the research behind attachment and the literature, you can find me at Dr. Jenica on Instagram, D R J E N I C K A.

Dr. Engler (46:57):

Amazing. I will, we will be linking that in the show notes. Um, definitely follow Jennica’s Instagram cuz as I said that all the content that she’s posting there is really gold. So if this is something that you guys are interested in, definitely check it out. So thanks again, Jenica. Thank you everyone.Thank you everyone for listening, and I hope you all have a wonderful day. Thank you so much for listening. If you enjoyed this episode, please subscribe, leave a review and share this episode with a friend who can benefit from it. I also love hearing from my listener, so feel free to DM me on Instagram at my sleeping baby or send me an email at Until next time, have a wonderful restful nights.

Never miss an episode. Subscribe now!